Improving the Radiation Resistance of the Fiber via Bismuth Depositing

Erbium-doped fiber (EDF), bismuth-erbium co-doped fiber (BEDF1) and BEDF with bismuth deposited on the fiber surface (BEDF2) were fabricated. Leveraging the Geant4 toolkit, the theoretical models of BEDFs are established. When the thickness of the bismuth deposited layer is 5 μm, the energy deposited in core is reduced by 49.66% (5.91 MeV). The energy deposited in core is reduced by 19.7% (1.06 MeV) when Bi<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3+</sup> ions concentration is 10 wt%. EDF, BEDF1 and BEDF2 were irradiated with 0.3, 0.5, 0.8 and 1.5 kGy doses of Co<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">60</sup> source. After radiation with 1.5 kGy, radiation-induced absorption (RIA) of BEDF2 at 1300 nm is 20.31% (1.01 dB/m) lower than that of BEDF1. The radiation induced gain variation (RIGV) and fluorescence lifetime of EDF are decreased with the increase of irradiation dose, while the RIGV and lifetime of BEDF1 and BEDF2 both increased initially and then decreased linearly. The normalized gain of BEDF2 is increased by up to 1.08 dB/m after 0.5 kGy radiation. Bismuth ions in the fiber core improves the radiation resistance of the fiber, and those deposited on the fiber surface further improve the radiation resistance. The research results have reference value and application potential in radiation environment detection and space satellite positioning.